Dyson argues that Rumsfeld was a paradox: a bureaucratic in-fighter who wanted to be in control of decision-making but, once in control, believed rather fatalistically that he and others could have relatively little impact on the course of events. This "paradoxical combination of a bureaucratic infighter style and a highly complex, somewhat fatalist worldview" (p.345) produced results that, given the larger context of the Bush administration's policy process, were nothing short of disastrous.
Here are a few key sentences from the article's conclusion (p.344):
"The case of Rumsfeld and Iraq points up the dangers of a 'CEO-president' and weak national security advisor.... The danger with a president as hands-off as Bush is that the principals are left to fight things out among themselves, and the most skillful and ruthless among them prevails. Of course, the most skillful and ruthless are not necessarily those with the best ideas."Drawing on, among other material, interviews with some of those who served in the Bush administration, Dyson's article notes that Rumsfeld was not ideologically committed to the Iraq war in the way that, for instance, his deputy Paul Wolfowitz was. This raises the question of what Rumsfeld's time as Sec. of Defense would have been like if the Iraq war had not been launched. My recollection is that during the period just after 9/11, Rumsfeld's public pronouncements, while they could be irritating in tone, were sometimes blunt (in a good way) and sensible. He seemed to manage the initial fall '01 operation in Afghanistan (Operation Enduring Freedom, as the Pentagon styled it) reasonably well, despite the failure to capture Osama bin Laden. For much of Rumsfeld's tenure, the war in Afghanistan was on a fairly low boil, as U.S. attention and resources focused on Iraq and the Taliban regrouped and bided their time. It's difficult to predict exactly what would have happened, say with respect to Afghanistan, if the Iraq invasion hadn't taken place. But on the evidence of Dyson's article, "the interaction of Rumsfeld's style with the styles of those around him and the nature of the issues" (p.345) would have meant that, even if the Iraq war hadn't occurred, Rumsfeld's time in office would have produced unsatisfactory results.